Sculpting with Dynamic Topology, using Inflate Brush, blue Artifacts appear
This is because of bleed through from the inner faces, facing the opposite direction. The darker color indicates the Normals direction. Try to never have interior faces near the sculpting surface while sculpting. If the hair is a separate object, you can completely remove inner faces, as they serve no purpose.



Notice that you will have to do this before you begin sculpting, as sculpting directly affects changes to the mesh. In order to salvage your mesh, you will have to just clean up as carefully as possible, using the Smooth brush and such tools.